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Why Starvation Diets Don't Work

webadmin - Posted on 01 April 2011

1. Very low calorie diets slow down your metabolic rate.

The first thing that occurs during a severe calorie shortage is a decrease in your metabolic rate. The lower your calories, the slower your metabolism becomes. This metabolic slowdown is well documented. When calories are restricted, your metabolism decreases by at least 20-30%. With severe calorie restriction, some studies have shown that resting metabolism can become depressed by as much as 45%! This is why, after prolonged low calorie dieting, you can eat very little food and still not lose weight. This also explains why it is so difficult to lose those last 10 or 20 pounds.

2. Very low calorie diets make you lose muscle.

The most devastating effect of a very low calorie diet is the loss of muscle tissue. Once the starvation alarm is triggered, your body begins looking for ways to conserve energy. Muscle is metabolically active tissue. Getting rid of it is the body's way of decreasing energy expenditure. It's easy for your body to use muscle for energy. This process is known as gluconeogenesis - converting muscle into glucose. This includes skeletal muscles, internal organs, and even your heart muscle!

Study after study has shown that very low calorie diets without exercise will always cause 40-50% of the weight loss to come from muscle. Many starvation diets, especially those that are very low in carbohydrates, cause large losses in water weight. Between the loss of water, glycogen and muscle, fully 75% of the weight you lose on many starvation diets is not fat! The initial weight loss on most starvation diets is very deceiving, giving you only the illusion of success. Even with exercise, if a diet is too restrictive, much of the weight loss will still be muscle.

The chief fat storing enzyme is called Lipoprotein Lipase (LPL). When you drop your calories too low, your body will produce more LPL and less fat burning enzymes. In other words, when you don't eat enough, your body changes its chemistry to make it easier to store fat in the future.

4. Very low calorie diets decrease output of thyroid hormone.

The thyroid gland is largely responsible for the regulation of your basal metabolic rate (the rate at which you burn calories at rest). When your body senses a severe reduction in calories, there is a corresponding reduction in the output of active thyroid hormone (T3). The result is a decrease in your metabolic rate and fewer calories burned.

5. Very Low calorie diets increase the chance of rebound weight gain.

Almost everyone loses weight initially on a very low calorie diet, but it never takes long before the body catches on and starts conserving energy. That's when you hit a plateau. Once you hit the plateau, it becomes much harder to keep losing weight, even if your calories are extremely low. This lack of continued results, combined with gnawing hunger pangs and insatiable cravings, usually causes people to give up out of sheer frustration. They go off their diet, the weight creeps back on, and their body fat ends up back where they started - only now they have less muscle and a slower metabolism.

With a slower metabolism, what used to be a maintenance level of calories now becomes a surplus, and the weight comes right back on. Most people gain back all the weight they lost - and some gain back even more, leaving them fatter than when they started. This up and down pattern of weight loss and weight regain is commonly known as the "yo-yo cycle," and it often continues for years or even for an entire lifetime. With each repeated bout of dieting, your metabolism becomes less and less efficient and you can actually become progressively fatter while eating less food.